Add Video.testVideoSeeking test.

tools/chrome_proxy/webdriver/video.py

Index: tools/chrome_proxy/webdriver/video.py
diff --git a/tools/chrome_proxy/webdriver/video.py b/tools/chrome_proxy/webdriver/video.py
index 32e9aa3a7e576ba84d2a3da4b664f04be96fd408..4af0670ee9e07d28d934e04a84374ac038d57d34 100644
--- a/tools/chrome_proxy/webdriver/video.py
+++ b/tools/chrome_proxy/webdriver/video.py
@@ -83,6 +83,59 @@ class Video(IntegrationTest):
           "metric doesn't match expected! Metric=%s Expected=%f Actual=%f"
           % (metric, expected[metric], actual), places=None, delta=0.001)
 
+  # Check that the compressed video can be seeked. Use a slow network to ensure
+  # the entire video isn't downloaded before we have a chance to seek.
+  @Slow
+  @NotAndroid

[RyanSturm, 2017/05/22 21:32:01]

t.FindElement(By.ID, 'video').click() might work on android if you can make a
click work instead of .play()

[Robert Ogden, 2017/05/22 21:34:53]

this test can't be android because ` with
TestDriver(control_network_connection=True) as t:`

[Tom Bergan, 2017/05/22 22:18:36]

I added a comment explaining why I added control_network_connection=True. Any
thoughts about how we might get this to run on Android?

I believe network emulation works on android when you open DevTools via device
inspection. Any idea why control_network_connection doesn't work on Android?

[Robert Ogden, 2017/05/22 23:00:27]

From what I came across implementing the feature, network emulation only worked
with device emulation which only works on desktop. But that was all external
sites, maybe there's a way to do it I don't know about. Feel free to file a bug
on me if you think there should be a way to do this and I'll look into it

[RyanSturm, 2017/05/22 23:09:16]

Thanks for the comment. Let's land as is.

+  def testVideoSeeking(self):
+    with TestDriver(control_network_connection=True) as t:
+      t.SetNetworkConnection("3G")
+      t.AddChromeArg('--enable-spdy-proxy-auth')
+      t.LoadURL('http://check.googlezip.net/cacheable/video/buck_bunny_640x360_24fps.html')

[RyanSturm, 2017/05/22 21:32:02]

nit: can you split this over 2 lines (80 char limit)

[Tom Bergan, 2017/05/22 22:18:36]

Done.

[RyanSturm, 2017/05/22 23:09:16]

Not seeing the change here.

[Tom Bergan, 2017/05/22 23:15:14]

Done for real.

[Tom Bergan, 2017/05/22 23:16:47]

Err, I fixed the wrong one. Now fixed for real.

+      # Play, pause, seek to 1s before the end, play again.
+      t.ExecuteJavascript(
+        '''
+        window.testDone = false;
+        const v = document.getElementsByTagName("video")[0];
+        let first = true;
+        v.onplaying = function() {
+          if (first) {
+            v.pause();
+            first = false;
+          } else {
+            window.testDone = true;
+          }
+        };
+        v.onpause = function() {
+          if (v.currentTime < v.duration) {
+            v.currentTime = v.duration-1;
+            v.play();
+          }
+        };
+        v.play();
+        ''')
+      t.WaitForJavascriptExpression('window.testDone', 10)
+      # Check request was proxied and we got a compressed video back.
+      # We expect to make multiple requests for the video: ensure they
+      # all have the same ETag.
+      video_etag = None
+      num_range_requests = 0
+      for response in t.GetHTTPResponses():
+        self.assertHasChromeProxyViaHeader(response)
+        rh = response.response_headers
+        if ('content-type' in rh and 'video' in rh['content-type']):
+          self.assertTrue('etag' in rh),
+          self.assertEqual('video/webm', rh['content-type'])
+          if video_etag == None:
+            video_etag = rh['etag']
+          else:
+            self.assertEqual(video_etag, rh['etag'])
+          if ('range' in response.request_headers and
+              response.request_headers['range'] != 'bytes=0-'):

[RyanSturm, 2017/05/22 21:32:01]

Are all the range requests of the form 0-? I thought you might want to look for
others as well.

[Tom Bergan, 2017/05/22 22:18:36]

s/num_range_requests/num_partial_requests/

When the media player plays a video, it first makes a request with "Range:
bytes=0-" (not the trailing slash). This is a "full" request as it requests
everything from byte 0 onwards. It's equivalent to an ordinary request that
doesn't have a range header.

To implement seeking, the player makes a partial request (like "Range:
bytes=500-600"). The intent is to make sure the media player made at least one
partial request, since the goal of the test is to ensure that we make an initial
request followed by at least one partial request.

Let me know if I should clarify this further.

[RyanSturm, 2017/05/22 23:09:16]

Ah I see. I read the condition wrong. Thanks for renaming the variable.

+            num_range_requests += 1
+      # Also make sure that we had at least one Range request.
+      self.assertGreaterEqual(num_range_requests, 1)
+
   # Check the frames of a compressed video.
   @Slow
   def testVideoFrames(self):